Infections of the summer

July 2001

---Philip A. Brunell, MD

With the coming of summer, we must think of different etiologic agents as the cause of illnesses than we think of during the previous months. Our contacts with others and with the outdoors increase. In addition, many will travel to different areas where they may encounter agents other than those they would in their usual environment.

When summer approaches, does respiratory disease tend to wane? For those of us who still cling to antibiotic prophylaxis for frequent otitis, it is time to consider a moratorium or just stopping completely. In this season of the year, enteroviral infections increase in frequency. When we see children with signs of meningitis, enteroviruses rise to the top of the list, especially in those who have received the conjugate Haemophilus influenzae type b or Streptococcus pneumoniae vaccines. Meningitis, or even a septic picture, in these infants should make us consider an enteroviral cause. Aseptic meningitis was seen most frequently in school-aged children until a decade or so when the age of infection seems to have shifted to infants and newborns. Enteroviruses can be detected by PCR where available, so that prolonged courses of therapy for suspected bacterial meningitis could be avoided if a positive test can be obtained, or if on clinical grounds bacterial infection can be ruled out. Unfortunately, enterovirus PCR may be difficult — if not impossible — to obtain.

Enteroviral infections

During the past few years, previously unrecognized syndromes have been associated with enteroviral infections, some of which have not yet been seen in the United States. Epidemics of hand-foot-and-mouth disease have occurred in some Asian countries. It is caused by enterovirus 71 and was associated with severe pulmonary disease and encephalitis. Many of the cases were fatal. Similarly, there have been sporadic episodes of hemorrhagic conjunctivitis caused by enterovirus 70 and Coxsackie A 26. Some of these have been associated with paralytic disease. Epidemics of hemorrhagic conjunctivitis also have occurred in Florida and in the Caribbean.

Although summer rashes are frequently ascribed to enteroviruses, one should be certain to rule out other causes. It is prudent not to attribute an illness associated with rash to an enterovirus in the absence of similar cases, ie, an epidemic and if no systemic symptoms are present. Contact dermatitis can be caused by contact with plants or by sunscreens, and photosensitivity can result from the use of drugs, eg, doxycycline. Papulovesicular rashes most commonly are due to insect bites during this season.

Tick bites can produce a variety of illnesses in endemic areas. Lyme disease is a major concern in the Northeast but does occur in certain areas of the Pacific Northwest and the Midwest. It has been pointed out that “Borreliaphobia” may be becoming a greater problem than Lyme disease itself. It is strongly recommended that one not get Lyme titers to explain fatigue, depression or vague neurological symptoms. When I was in Los Angeles, most of the “Lyme disease” referrals fell into the latter category. We did see an occasional patient with erythema chronicum migrans who had just returned from an endemic area. The issue of prophylaxis following tick bites has surfaced again. The article will appear in a July issue of The New England Journal of Medicine but the discussion already has started. The commentary accompanying the article by Gene Shapiro, MD, provides the rationale for not giving prophylaxis although it involves only a single dose of doxycycline. For those who live in endemic areas and have been given Lyme vaccine (LYMErix, GlaxoSmithKline), it is time to check whether an additional dose is due at this time.

Travel history

It is important, especially this time of year, to take a good travel history. Some patients returning from endemic areas also my have acquired ehrlichiosis, babesiosis or Rocky Mountain spotted fever. The latter is much more common in the East than the Rocky Mountains!

Many children will be spending a lot of time in swimming pools this summer. Transmission of Escherichia coli, Cryptosporidia and Giardia resulting in diarrheal disease are the common agents transmitted in pools. In Texas we had two children come in the same week who had been swimming in warm lakes who had Naegleria meningitis. This may be difficult to diagnose especially if one does not think of it. The spinal fluid examination is similar to that in bacterial meningitis but etiologic diagnosis will require special help.

During the summer season many families travel. Not only should requirements for vaccines against exotic diseases, eg, yellow fever and typhoid and antimalarial prophylaxis be checked, but also attention should be given to diseases for which vaccines are commonly used in the United States. Although children may not live in areas in the United States where hepatitis A vaccine is routinely given, this may be indicated for travel in certain places here and abroad. Adequate immunization against diseases, eg, measles and pertussis, should be assured.

Finally, it is important to remember that in addition to shedding clothing and schoolbooks, the summer brings shedding of inhibitions and opportunities for new friendships. It is a good time to counsel adolescents about how to protect themselves against sexually transmitted diseases. The June Pediatrics contains an excellent statement, which should be read by all.